War against the Islamic State

Overview

Many states began to intervene against the Islamic State (IS), in both the Syrian civil war and the War in Iraq (2013–2017), in response to its rapid territorial gains from its 2014 invasion of Iraq, widely condemned executions, human rights abuses and the fear of further spillovers of the Syrian civil war. In later years, there were also minor interventions by some states against IS-affiliated groups in Nigeria and Libya. All these efforts significantly degraded the Islamic State's capabilities by around 2019–2020. While moderate fighting continues in Syria, as of 2026, IS has been contained to a small area and force capability.

Overview adapted from Wikipedia, licensed under CC BY-SA 4.0.

Significance

The war against the Islamic State drew together a broad multinational coalition—operating under CJTF–OIR—in response to IS's rapid territorial expansion following its 2014 invasion of Iraq, its widely condemned executions, and its human rights abuses, as well as concern over further spillover from the Syrian civil war. Member states conducted military operations across Syria and Iraq, with smaller interventions later extended to IS-affiliated groups in Nigeria and Libya. The combined effort significantly degraded IS capabilities by around 2019–2020, reducing the organization from a proto-state controlling large contiguous territory to a contained force operating in a small area. As of 2026, fighting in Syria continued at a reduced level, with IS constrained in both territorial reach and force capability, representing a substantial but incomplete outcome for the coalition.

Forces & casualties

Commanders (167)